1. Field of the Invention
The present invention relates to an apparatus for use in replacing a ring gasket carried by a subsea wellhead connector.
2. Description of the Prior Art
In the drilling of oil and gas wells at an underwater site, a coupling is used for connecting subsea wellhead components to one another in sealed or pressure-tight relation. It is usual for the upper portion of the coupling to contain a seal or ring gasket retained in place by a suitable device, this ring gasket being brought into sealing relation with a lower device previously-installed at the underwater location. The ring gasket used in the coupling may commonly be designated as a "RX", "CX", "AX" or "VX" ring gasket depending upon the manufacturer of the gasket.
When the underwater coupling is disconnected, it is desirable to replace the previously-installed ring gasket with a new one to insure a pressure-tight fit upon re-engagement of the coupling assembly. It is also desirable to inspect the surface of the old gasket for unusual deformations that would indicate damage to the sealing shoulders which mate with the gasket. After the underwater coupling is disconnected, the entire upper portion of the wellhead connector coupling with its attached ring gasket may be retrieved to the deck of surface vessel conducting the well operations. In shallow water depths, the retrieval operation does not cause an unnecessary amount of downtime. The ring gasket is usually removed from a ring gasket retainer assembly, such as the one disclosed in U.S. Pat. No. 3,350,103, entitled "Seal Ring Holding Device", issued Oct. 31, 1967 to A. G. Ahlstone, by disengagement of a split ring normally held in position about the ring gasket by a series of spring-loaded circumferentially spaced plungers.
In deeper waters, to retrieve the ring gasket retainer assembly to the surface would require considerable time and entail an expense of approximately one million dollars due to the retrieval of the coupling to the surface along with thousands of feet of pipe to which it is connected.
Accordingly, it is desirable to present a method and apparatus for installing a new ring gasket into a subsea coupling, without having to retrieve the coupling to the surface. It is also desirable to retrieve the previously installed ring gasket for inspection, and from a depth generally below that at which a diver can operate, say, 5000 feet or more.